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MEMS Filter With Voltage Tunable Center Frequency And Bandwidth - Patent 8111114

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MEMS Filter With Voltage Tunable Center Frequency And Bandwidth - Patent 8111114 Powered By Docstoc
					
				
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Description: FIELD The present invention relates to MEMS filters, and, more particularly, to voltage tunable MEMS filters.BACKGROUND High-Q microelectromechanical (MEMS) resonators are ideal replacements for conventional lumped LC components in radio frequency applications. Ladder and lattice filters built from MEMS resonators have better shape factor due to their inherenthigh mechanical quality factors (Q.about.1000-10,000) compared to quality factors of electrical LC components (Q.about.200). However, a major disadvantage of current MEMS filters is the lack of frequency and bandwidth tunability. Therefore, what is needed is a MEMS filter with a tunable center frequency and bandwidth.SUMMARY A tunable MEMS filter is disclosed. The tunable filter has a substrate having a first isolated substrate area and a second isolated substrate area. The tunable filter also has first and second anchor points coupled to the substrate. Thetunable filter further has a base coupled to the first and second anchor points by first and second coupling beams, respectively. The tunable filter has a dielectric layer coupled to the base. The tunable filter further has an input conductor coupledto the dielectric layer. The tunable light filter also has an output conductor coupled to the dielectric layer, wherein the first isolated substrate area is configured to receive a first substrate voltage with respect to the base; and the secondisolated substrate area is configured to receive a second substrate voltage with respect to the base. A method of tuning a center frequency and a bandwidth of a MEMS resonator filter is also disclosed. A first bias voltage is adjusted between a base layer and input and output conductor layers. A second bias voltage is adjusted between the baselayer and isolated substrate areas below at least a portion of the base layer. The center frequency and the bandwidth of the MEMS resonator filter are determined until the adjustments to the first bias voltage and the second